1. Field of the Invention
Embodiments discussed herein relate to semiconductor devices.
2. Background of the Related Art
A power semiconductor device used as a power conversion device or the like includes: a semiconductor chip; a laminated substrate including an insulating plate having a circuit board and a metal plate formed in a front surface and a rear surface thereof, respectively, the semiconductor chip being provided on the circuit board via solder; and a radiation base having therein the laminated substrate provided via solder. A radiation fin is further attached via a thermal compound to a copper-based rear surface of a power semiconductor device having such a constitution housed in a case. Moreover, the power semiconductor device is heated in order to solder-bond the semiconductor chip, laminated substrate, and radiation base. In this case, because there is a difference in the thermal expansion coefficient between the respective members, the radiation base will be warped. If a gap is produced between the warped radiation base and the radiation fin, the thickness of the thermal compound becomes uneven and the radiation performance will degrade.
Then, a work-hardened layer is formed in the radiation base so as to be able to control the warping of the radiation base. Thus, there is known a method for bringing a radiation base and a radiation fin in close contact with each other and making the thickness of a thermal compound uniform to suppress a degrade in the radiation performance (e.g., see Japanese Laid-open Patent Publication No. 2004-214284).